The home had been undergoing renovation for about a month and was vacant, Vanderhorst said.

The Gas Co. said a preliminary investigation has determined that the gas main pipeline and the service line up to the gas meter were in safe operating condition, and that no leaking was detected.

The cause of the explosion remained under investigation. Vanderhorst told the Riverside Press-Enterprise that he believes gas built up in the house before the blast.

A home next door was on fire, and another had lesser damage, Vanderhorst said.

Wayne Keller and his wife, holding their dog, stood outside their badly damaged home, near the house that was leveled.

"We heard an explosion, and we got out of our bed, and when I came into the front room, both windows on that side of the house, the far side of the house, nothing but fire and flames," he told KABC-TV.

The outside garage door had been blown inward.

"It was mayhem," Keller said. "You could hear the gas line just going like crazy."

The chimney at Keller's home also was destroyed, and firefighters had to chop holes in the roof to battle the fire. "It's uninhabitable," he said.

Other neighbors described being awakened by the loud explosion.

"I thought it was an earthquake," Mary Holley told the Riverside Press-Enterprise. "My son said it sounded like a car hitting our house."